1. Field of the Invention
This invention relates to a die cutting press for cutting a number ofareas defining individual parts, from a web or sheet substrate in which the parts are arranged as rows extending along the length of the web or sheet, as well as in cross-rows across the width of the substrate. In particular, the invention relates to a die cutting press which includes die unit indexing and registration apparatus that indexes the die unit across the width of the substrate to bring the die unit into general alignment with each part in a cross-row thereof and then registers the die unit with each individual part before effecting the cutting operation.
2. Description of the Prior Art
Die cutting presses are illustrated and described in U.S. Pat. Nos. 4,555,968, 4,697,485 and 5,212,647, all of which are assigned to the assignee herein. The presses of the ""968, ""485 and ""647 patents are provided with a floating bolster which supports a die unit in which the cutting die is located above a substrate having a part therein to be cut, and in which the die unit is shifted to accomplish the cutting operation after precise registration of the cutting die with the area of the substrate defining the part to be cut. Although especially useful for die cutting of a web having a series of part-defining areas along the length of the web, the presses of these patents also have utility for cutting of parts from a sheet having a plurality of parts in a singlerow extending along the sheet in the direction of delivery of the individual parts to the die cutting area of the press.
In the die cutting presses of the above-referenced patents, X axis registration (in the direction of feed or travel of the sheet or web into the press) of the die unit is accomplished by control of the infeed mechanism. Y axis registration (across the width of the web or sheet) is controlled by a servo connected to the bolster to thereby shift the die unit. Rotation of the bolster as required for xcex8 angle adjustment is carried out by another servo operable coupled to the bolster for shifting the bolster and thereby the die unit transversely to the direction of infeed of the substrate.
In the die unit registration system of the ""647 patent, a registration system is provided in which one or more indicium fixed on the bolster of the press is utilized to indicate the position at which indicium on the substrate web appear when defined areas of the elongated web are in desired predetermined relationship relative to the die unit supported on the floating bolster. A camera vision system is employed to compare the position of indicia on the substrate with a reference indicia in computer control apparatus. The system is then capable of operating the infeed mechanism, and the Y and xcex8 angle adjustment servos connected to the floating bolster to simultaneously move the substrate along the X axis, to shift the bolster along the Y axis, and to rotate the bolster about its pivot axis to adjust the xcex8 angle, as required to precisely align the die unit with part-defining areas of the substrate which have been successively moved into general alignment with the die unit.
The die cutting presses of the ""968, ""485 and ""647 patents are capable of very precisely aligning the die cutting unit with the part to be cut from a web or sheet on a repeatable basis and at a relatively high output rate. However, a sheet or web having a series of individual defined areas comprising parts to be cut by the die unit presents a much more difficult registration problem where the individual parts are arranged in rows extending along the length of the sheet or web, as well as a series of cross-rows of part-defining areas in that it is necessary to shift the die unit laterally of the sheet or web into general alignment with the part-defining area of the substrate in another part area of a cross-row thereof.
The Y axis servo connected to the floating bolster of the ""968, ""485 and ""647 patents was not designed or finctional to shift the entire floating bolster to an extent to bring the die unit into general alignment with the next adjacent part-defining area of the sheet or web in a respective cross-row of the part areas, and such lateral movement would not have been practical because the floating bolster must rotate to perform the xcex8 registration function.
As a consequence, the die unit must be reliably and efficiently shifted laterally of the supporting bolster to bring the die unit into successive general alignment with the parts to be cut in cross-rows of the part-defining areas of the web or sheet. In addition, the die unit must be precisely re-aligned with each part-defining area after or as the die unit is brought into a general alignment with a respective part area independently of the die registration that has been accomplished with the immediately preceding part area to be cut.
The problem presented by the need to cut individual parts from a sheet or web substrate in which the individual part-defining areas are arranged as rows extending along the web or sheet as well as across the sheet is greatly exacerbated when the material to be cut comprises a substrate that has undergone distortion or warpage as a result of the process of manufacturing the product. Exemplary in this respect are substrates such as a plurality of screen printed images on a sheet, web or other backing, in which the images are subject to printing inaccuracies, substrate distortion or other factors that cause the individual images to not all be precisely in the same relative positions on the substrate. Other exemplary products in this respect comprise bio-sensors, and a series of flexible electronic circuit boards or the like in arranged in longitudinally and laterally extending rows on the web or sheet. Electronic circuit boards, for example, have copper areas defining circuits formed or etched thereon. The forming and etching procedures often cause the web or sheet to become distorted as a result of non-uniform forces on the substrate which are a result of the manufacturing process.
Therefore, there has been a need for a die cutting press having the die unit registration attributes ofthe presses illustrated and described in the ""968, ""485 and ""647 patents, and especially the camera vision system of the ""647 patent, which is capable of precisely alignment the die unit with the parts to be cut from a web or sheet in which the individual parts are arranged on the substrate both as rows extending longitudinally of the substrate, as well as in cross-rows thereof spaced laterally one from another. In addition, the die cutting press should be capable of precisely aligning the die unit with each individual part-defining area to be cut, even in those circumstances where the substrate to be processed is not perfectly flat and is somewhat distorted and warped as the result of the manufacturing process for the substrate, or the printing procedures as result for example in screen printing operations.
Object and Summary of the Invention
It is therefore an object of the present invention to provide a die cutting press for precision cutting of individual part-defining areas arranged along and across a relatively thin substrate of the type in which the press has a base platen, a bolster shiftably and rotatably mounted on the base platen, and a die unit supported on and movable with the bolster and wherein an indexing device is connected to the die unit that is operable to successively shift the die unit relatively to the bolster into general alignment with successive ones of the individual defined areas thereby permitting precise alignment of the die unit with the defined area to be cut by simultaneous X axis adjustment of the infeed, and Y axis and xcex8 angle adjustment of the bolster with individual defined areas.
A further important object of the invention is to provide a die cutting press of the type described in which the registration mechanism is operable to rotate the bolster different amounts and to shift the bolster different distances to obtain registration of the die unit with an individual part-defining area generally aligned with the die unit depending upon the distance of the particular individual part area aligned with the die unit from the pivot axis ofthe floating bolster. Thus, the registration system automatically compensates for the fact that even though the pivot axis for the bolster is fixed, the bolster must be rotated through different angles and must be shifted different distances depending upon the location of the part to be cut from the substrate with respect to the pivot axis of the bolster.
A further object of the invention is to provide die unit registration mechanism for a die cutting press which includes at least one digital camera operable to receive an image of indicium associated with a respective part-defining area of the substrate and that generates data indicative of the position of the indicium sensed by the camera, along with a reference unit providing reference image data representative of the desired position of the indicium associate with the respective part-defining area and thereby that part area with respect to the die unit, and a comparator for comparing the camera-generated indicia with the reference indicia for controlling simultaneous operation of the X axis infeed adjustment, and the Y axis and xcex8 angle adjustment servos connected to the bolster to bring the die unit into precise registered alignment with the part-defining area to be cut.
Also an object of the invention is to provide die unit indexing and registration mechanism for a die cutting press in which an indexing device is provided for successively shifting the die unit across the width of a substrate having longitudinally and laterally extending rows of parts to be cut, in a Y axis direction independently and at a different rate than the Y axis adjustment of the die unit supporting bolster of the press, thereby increasing the speed of operation of the press.
Another object of the invention is to provide a die cutting press as described in which the die unit is successively indexed in one direction across the width of the sheet or web tocut parts from a cross-row thereof, and then successively indexed in the opposite direction across the width of the sheet or web to cut parts from the next adjacent row thereof, thus minimizing movement of the indexing mechanism by virtue of the serpentine path of travel thereof.